In early 1940s rural Donegal, 12-year-old Hugh Green decided school was a waste of time and he was better off out in the world helping his struggling family.

With steady work hard to come by and no skills to his name, the young Green displayed innate entrepreneurialism from the start. He would gather potatoes for three shillings a day and one day got offered the choice of either being paid or taking as many spuds as he could carry.

He knew he could sell them to his aunt who ran a hotel, so he opted to take a 64-kilogram bag. But he had to carry it some distance to the hotel and didn't dare set it down for fear he couldn't lift it again. His efforts paid off - he got 12 shillings and sixpence from his aunt, four times the amount he would have earned in wages.

Shortly before he died in Auckland 68 years later, the NBR Rich List estimated his wealth at $350 million. On top of this he had established the $50m Hugh Green Foundation, which donates about $2m to charity each year.

"It was all about the deal; the money was really irrelevant," says his son, John Green.

When Hugh was born, the Green family owned the Central Hotel in Raphoe, eastern Donegal, and were comfortably off for the times. But the hotel was lost through his father's drinking - an event that shaped Hugh's life.

Hugh Green Sr was a cattle dealer and taught his son the trade. At the cattle fairs of Donegal, Hugh Jr learned valuable skills in deal-making and how to read people. It was also the beginning of a lifelong passion for the beasts.

But there were few prospects in Ireland, and, at the age of 17 - like most of his generation - he emigrated. He spent the next few years working on hydro schemes in Scotland, railways in England, cutting sugar cane in Queensland and digging trenches in Melbourne.

Along the way he befriended Barney McCahill, another young Donegal man. The pair thought they were working their way home when they landed in Wellington in 1952. They recruited a gang of Irishmen to bid for contracts digging utilities trenches. Green would go through the tenders columns in the newspapers (no mean feat, given his basic reading skills) and they began winning contracts. Green & McCahill was born.

The hardworking Irishmen were more efficient than their competition. They would leave stretches of a trench around the streetlights undug during the day, so they could come back at night and utilise the lighting to lengthen their working day.

While McCahill sorted out the labour, Green would look after the business end. Had he been educated he might have become a lawyer, John Green believes, because he became extremely adept at reading contracts.

"I could find ways of making money hidden in a contract that nobody else could see," Hugh wrote in his 2011 autobiography. Green & McCahill would do things such as charge for unrolled cable left at the end of a trench, because the contract didn't say it couldn't.

The firm continued to grow, winning the Hamilton Arterial Route contract in 1960 and later building the Haast Pass road. Major projects to follow included the Huia dam south of Auckland, the huge Mangatangi water supply dam, and the Ngauranga Gorge and Te Marua water storage lakes near Wellington. There were also jobs in Australia and Fiji. From a staff of 79 in 1960 the firm grew to 500 employees.

"Everything we did was a bigger version of two simple processes - digging holes and filling them up again, and driving a hard bargain like you would with a cattle sale," Green said.

The firm had also begun making property investments, and when business suffered after the 1987 crash it shifted its focus to developing subdivisions.

Green had always banked land, and would farm his cattle on it in the meantime, John Green says. "He'd buy land as cheap as he could which was originally a long way from the city in those days, but, of course, now as the city's spread it's become more valuable."

Examples include 107 hectares at Long Bay on Auckland's North Shore, which the Green Group sold for $65m in 2007.

In the early 2000s, Green and McCahill decided to go their separate ways. Now the Green Group is a debt-free investment and property company.

Chief executive Seamus Brennan says Green took calculated risks and never moved quickly. He would canvass opinion from all sectors, including his staff, and then form a view.

Turning his experience in contracting to his advantage in property development was an example of how canny he was.

"He could see where he could close the loopholes from a contracting side of things, that he would have been very much trying to open when he was contracting."

He could also look beyond the first hurdle and see further down the track.

"Hugh might have looked at a [property financing] deal and said, 'well, if the worst comes to the worst . . . we've got the expertise to take that development and complete it ourselves'. It wasn't just a loan deal."

Chief financial officer Jane Porter says Green would ring his staff 10 to 15 times a day. He was feisty and tough, but also generous. "Above all he respected hard work and honesty and he really rewarded people who displayed that," she says.

He chased every debt, and kept the amounts of everything in his head.

Daughter Frances says he never learnt to use a computer, calling it "the magic box". "He couldn't really read and write that well, and he certainly couldn't spell."

He was hard on his children, but "you saw a different side of him when he went to Ireland", Frances says.

He had married Aucklander Moira Buckley in 1955 but was achingly homesick for years, only settling when he could afford to make regular trips back, she says.

He didn't have a drink until he was 53. "Because of his father, he was scared of it," John says.

He remained Irish in every way, including his refusal to support the Queen - when God Save the Queen was played at the movies, the Greens were not allowed to stand up - and his Catholicism.

His philanthropy went under the radar for years, his son says. "If you were Catholic and Irish, you were pretty much assured of a handout if you needed one. He'd just read something in the paper, someone looking to raise money, and he'd ring them up. He always felt he owed something back, that he'd done so well here.

The New Zealand Business Hall of Fame was created in 1994 by Young Enterprise Trust, and is presented each year with the support of Fairfax Media, Auckland Chamber of Commerce and Kaimira Estate. The 2013 gala dinner will be held on Wednesday, July 31, at The Langham, Auckland. Tickets are $225 each and can be ordered by phone on (04) 570 3980 or online at businesshalloffame.co.nz.